1. Field of the Invention
The present invention relates to the field of cheese manufacturing, more particularly to the field of cheese shaping and packaging, and more particularly to the field of construction shaped cheese units out of partial cheese segments.
2. Background of the Art
The principal solid constituent of milk is casein, a protein. When raw or pasteurized milk is allowed to stand in a warm place, it sours, and the casein is precipitated by the action of lactic acid bacteria. For example, in the case of pasteurized milk, in which these harmless bacteria have been killed, an acid “Starter” must be added. The thick precipitate (e.g., the curd) that results from the action of the lactic acid bacteria (a lacto bacillus) is separated from the thin, watery residue known as whey. This was the earliest method of producing cheese and it is still used to make pot cheese and cottage cheese, although curd prepared with rennet, which acts to speed the separation process, is generally a preferred method of manufacture today. The curd, however prepared, contains (in addition to the protein) most of the other food values of the milk, including butterfat, minerals, sugar, and vitamins. Cheese may be made from the milk of ewes, goats cows, or any other lactating mammal, with the flavor and nutritional content varying among species.
The next steps in the making of cheese include at least salting (for flavor and eventually to aid in curing) and pressing (to shape the cheese and eliminate more whey). The curd is then ready for curing and is stored under temperature-and humidity-controlled conditions for varying lengths of time. Some cheese, such as cream or cottage cheese, is not cured. In general, the longer the curing or aging process, the more pronounced the flavor of the finished product. During curing, gases are formed within the cheese, and in some types they are unable to escape, forming large pores or holes within a block of cheese. This produces the holes, or eyes, characteristic of, for example, Swiss cheese. To aid the curing process in the formation of particular forms of cheese, harmless-to-human spores of mold (e.g., blue-mold spores) are introduced into cheese. The manufacture of the blue-veined cheeses (Roquefort or blue cheese) uses blue mold spores added to the vein structure, and white-mold spores are sprayed on the surface of such cheeses as Brie and Camembert. This surface treatment produces a “bloomy” rind, which may be eaten or not according to personal preference. The rinds of other cheese are washed with whey or brine. Still other varieties of cheese that are sprayed with mold or have mold added to the underlying composition are rindless.
There are more than 2000 varieties of cheese known today, including variations of original types, such as American Swiss cheese. Regardless of their animal sources, all cheese are divided into two basic categories; natural cheese and process cheeses. The latter, a recent development, are blends of several kinds of natural cheeses with the addition of emulsifiers. While they may keep longer than natural cheeses, their nutritive value is the same.
The butterfat content of cheese, that is, the amount of butter fat remaining in the cheese solids after all moisture has been removed, varies according to whether the cheese has been made with whole milk, skim, or part-skim milk, or enriched milk. Skim-milk cheese has a butterfat content of 0.5 percent or less. Average cheeses, such as Cheddar, Gouda, or Camembert, have a fat content of from 45 to 50 percent. Double and triple creme cheeses have 60 to 75 percent butterfat. In addition to typing by fat content, cheese can be categorized by consistency or moisture content. Thus, there are hard-grating cheeses, ripened longer and with sharp flavor (for example, Parmesan), hard cheeses (for example, Cheddar), semisoft cheeses (for example, Roquefort or Limburger), and soft cheeses (for example Camembert or cottage cheese). The latter two categories are the more perishable, but storage times vary for all cheese. In general, cheese for home consumption should be kept under refrigeration at between 1.5° C. to 4.5° C. (35° F. to 40° F.) and securely wrapped to prevent drying out.
In cheese manufacturing, there is significant segmentation, waste, scrap and trim of the cured and processed cheese that can be lost during manufacturing and packaging steps. It is common practice to process the waste or scrap into sellable forms, such as processed cheese or cheese spreads.
In the manufacture of bulk forms of cheese by conventional means, a milled or stirred, salted curd is filled into a bulk form, such as either a 500 pound (227 kilo) “barrel” or a 640 pound (291 kilo) cube. After filling the form, vacuum probes are placed into the barrel or block of loose curd to remove residual whey. The bulk container may be tipped to allow excess whey to be drained away. The bulk containers are then placed in a vacuum chamber to finish the forming and draining of the cheese mass. This probing, tipping and vacuuming process is somewhat cumbersome and can be a point for contamination of the cheese with undesirable microorganisms and or foreign material.
One improvement of this process that is practiced in the industry with increasing prevalence is to convey the milled or stirred salted curd into a forming tower (e.g., a Wincanton tower) commonly used for the final draining and forming of cheese into 40 pound (18.2 kilo) blocks. The cheese exits the tower thoroughly drained and formed into a semi-solid block. The innovation has been to break this semi-solid block into smaller pieces, convey the smaller pieces into the 227 kilo barrels or 291 kilo block, apply vacuum and/or pressure, and sealing the liner or bulk container. The cheese then tends to re-knit into a solid form during a cooling and storage period (estimated 5-days for cooling and from days to weeks to months for cold storage).
Unless conditions of temperature, pH of the curd, rate of cooling of the curd, pressure/vacuum in the container, etc., are ideal, the cheese is formed with “mechanical openings and visible seams where the pieces of curd or cheese have been joined into the larger form of cheese. The cheese can easily fracture along these seams. Where much of the bulk cheese is used, these conditions are of little consequence, since the bulk cheese will be shredded or ground as an ingredients for later processing.
As previously noted, however, in some applications, including procurement by the USDA, there are numerous factors that are built into the valuation and grading of cheese, including United States Standards for Grades of Bulk American Cheese, effective Aug. 2, 1991, Sections 58.2455 through 58.2462.
The compacted product has the same essential cheese compositional quality as the original blocks formed, but may not be graded as high as the original material. This lower grading is the result of an anomaly in the grading procedures that does not rely entirely upon the sensory qualities or nutritional composition of the cheese, but also relies on structural factors that do not impact the taste or nutritional quality of the cheese. In particular, samples of cheese are graded by taking cores or plugs of cheese, and inspecting the cheese core to determine features such as pore content and fracture lines in the cheese. The more numerous the spacing or pores, the more fragile segmentation lines, and the appearance of other physical defects in the construction can dominate the grading, reducing the quality value of a cheese to a much lower grade, even though the actual content quality of the cheese is very high with respect to flavor and nutrition. The specifications for this testing are noted above in the U.S.D.A. Standards for Grades of Bulk American Cheese.
EP 0 711 504 B1 describes a method for increasing the eight of a curd by the addition of a transglutaminase (alone or in combination with a milk clotting enzyme, a rennet) into a solution containing milk or a milk protein. The process is carried out by adding the transglutaminase (with or without the rennet0 to a solution containing the milk or milk protein, heat-treating the solution to deactivate the transglutaminase (and optionally adding the milk clotting enzyme). The process may also be effected by first adding the rennet and allowing the enzyme to act on the milk or milk protein solution, and then adding the transglutaminase. In all cases, the transglutaminase is added prior to forming of the cheese curd or composition.
WO 97/01961 describes a process for making cheese comprising: a) adding to a milkcheese a transglutaminase, incubating for a suitable period, b) incubating with a rennet to cause clotting, and c) separating whey from the coagulate, and d) processing the coagulate into cheese. The transglutaminase mainatins the proteins within the cheese material during conventional cheese-making processes. The transglutaminase may be deactivated at a desired stage of the process by heat or other controls.
U.S. Pat. No. 5,686,124 describes a method for restructuration of raw meat for production of restructured raw meat by addition to the meat of transglutaminase The method for restructuration of raw meat for production of restructured raw meat by addition to the meat of transglutaminase comprises the further addition of phosphate (optional) and sodium chloride, with a subsequent temperature treatment. The cohesion and hardness of the restructured raw meat is improved, and it can be sold as a refrigerated meat product. EP 0201975 describes a method of the same general kind as the method of U.S. Pat. No. 5,686,124. However, in relation this prior art method a binding material of external fibrin must be used, which necessitates the use of fibrinogen and expensive thrombin. A preferred embodiment of U.S. Pat. No. 5,686,124, is characterized by the fact that the phosphate (if added), the transglutaminase, and the sodium chloride is added as an aqueous solution. This solution should preferably be as concentrated as possible. In this manner the subsequent mixing process for the raw meat components may be carried out without any difficulty.
U.S. Pat. No. 4,917,904 describes that the properties of meat can be modified by addition of transglutaminase, salt and a phosphate. This prior art, however, does not describe the use of an alkali metal phosphate, and furthermore, this prior art method is not a method for production of restructured raw meat, but a method for production of high temperature treated, smoked meat.
U.S. Pat. No. 5,518,742 describes the use of enzyme preparation for producing bound-formed food. An enzyme preparation for bound-formed food use which comprises transglutaminase, a casein and an edible surface active agent. The enzyme preparation strongly binds raw food materials, and the resulting bound-formed foods have an excellent taste and savor. The enzyme preparation for binding of raw food materials, comprises:
20–99% by weight of a protein selected from the group consisting of casein, calcium caseinate, potassium caseinate, sodium caseinate, casein-containing milk powder and mixtures thereof;
0.01–15% by weight of an edible surface active agent selected from the group consisting of a sucrose fatty acid ester and a sorbitan fatty acid ester; and
1–50,000 units of transglutaminase per gram of said protein in said preparation. It is generally known that, when a bound beef is prepared, binding of meat pieces to one another cannot be effected without the use of a binding agent. The reference has prepared prototype bound beef samples A, B and C by mixing such meat pieces with (A) 1% sodium caseinate only, (B) only transglutaminase in an amount of 1 unit per 1 g meat or (C) 1% sodium caseinate and transglutaminase in an amount of 1 unit per 1 g meat and then allowing each of the resulting mixtures to stand still at ordinary temperature for 30 minutes. Tensile strength (g/cm.sup.2) of each of the thus prepared prototype samples was measured using a rheometer manufactured by Fudo Kogyo Co., Ltd. Tensile strengths (g/cm2) of the three prototype samples were found to be A=25, B=41 and C=185, thus showing a pronounced synergistic effect caused by the combined use of transglutaminase and a casein. In general, binding of raw materials or cooking and processing performance of the bound product cannot be regarded as effective or acceptable when the tensile strength is less than 100 g/cm2. The enzyme preparation of this reference may further contain various optional ingredients, in addition to the essential active ingredients transglutaminase and caseins. One of such optional ingredients is a food filler. Any of common food fillers can be used without particular limitation, which include for example lactose, sucrose, maltitol, mannitol, sorbitol, dextrin, branched dextrin, cyclodextrin, glucose, starches such as potato starch, polysaccharides, gums, emulsifiers, pectin, oils and fats and the like. Of these, starches such as potato starch and branched dextrin are particularly preferred because they do not exert influence on the binding effect of raw food materials by transglutaminase and casein and they have no taste or odor. These food fillers may be used singly or as a mixture of two or more. Such food fillers are useful for giving characteristic properties to foods, especially those properties required in addition to the binding capacity, such as a juicy feeling, a good throat-passing feeling and a soft eating touch even when the food is cooled. In addition to these food fillers such as branched dextrin and the like, the enzyme preparation of the present invention may also contain proteins other than caseins, as other optional component, which include soybean proteins such as isolated soybean protein, concentrated soybean protein, extracted soybean protein, defatted soybean protein and the like; wheat proteins such as wheat gluten and the like and wheat flour which contains wheat proteins; corn protein; and egg proteins such as albumen, egg albumin and the like. These proteins also impart a binding function. The only actual example of the use of cheese material in the process is Example 29 wherein slices of cheese, meat and cucumber are layer with intermediate layers of the glue bonding the layers together. The transglutaminase bonds the casein in the mixture into essentially a glue that adheres the layers together, forming a definitive seam line and adding distinct contents component into the seam line (e.g., the casein or salt caseinate, and other ingredients within the glue).
U.S. Pat. No. 5,928,690 is directed to a process for improving the quality of pale, soft and exudative meat by treating meat with transglutaminase enzyme. The invention is particularly well suited for manufactured pork and turkey breast products such as canned or packaged hams and turkey breasts. The manufactured meat products have reduced cooking purge, improved binding of the muscle pieces and firmer texture. A process is disclosed for lessening, repairing or reversing the PSE (pale, soft and exudative) characteristics in meat, the process comprising treating a meat source having PSE characteristics with an aqueous solution consisting essentially of a selected quantity of transglutaminase at a temperature and for a time sufficient to lessen, repair or reverse the PSE characteristics of the meat source, the treating being prior to a curing procedure which includes cooking and/or smoking the meat source.
A number of patents or publications teach the use of the enzyme transglutaminase (also referred to hereafter as “TG”), also known as glutamate transaminase, to improve the water retention and texture of fish, fowl and animal meats, particularly ground or minced meats, soybean protein, egg albumin and casein containing products. For example, U.S. Pat. No. 4,917,904 to Wakameda et al. describes a process whereby TG is added to various meats, soybean protein, egg albumin or casein-containing mixtures to improve the texture thereof. Specifically, Wakameda et al. describe adding TG to ground fish meat, minced fish meat, fillet and lyophilized fish powder, ground or minced animal meat, and fowl and block meat to improve the water retention of the final ground or minced meat product. However, Wakameda et al. state that while TG enhances the water retention in such animal meat and fowl, the texture thereof becomes hard to masticate or chew. This difficulty in chewing the product is an undesirable property. Wakameda et al. do not teach the use of TG to lessen, reverse or repair the PSE condition or the effects of the PSE condition.
Examples of publications discussing TG effects include “Transglutaminase Mediated Polymerization of Crude Actomyosin Refined From Mechanically Deboned Poultry Meat”, Akamittath and Ball, Journal of Muscle Foods 3, 1992, 1–14; and “Strength of Protein Gels Prepared With Microbial Transglutaminase as Related to Reaction Conditions”, Sakamoto, Kumazawa and Motoki, Journal of Food Science, Volume 59, No. 4, 1994.
European published patent application 0 333 528 describes the genetic alteration of micro-organisms to produce TG and the addition of such genetically altered micro-organisms to ground meats to improve the texture of the ground meat when it is cooked. Generally, the genetically altered micro-organisms are described as being used with ground beef, soya, and casein, among other substances, to prepare ground meat products, sausages and cheeses. This publication does not teach the use of the TG-producing micro-organisms to lessen, reverse or repair the PSE condition or the effects of the PSE condition.
A number of approaches have been described in the art to prevent the development of the PSE condition. Exemplary references include U.S. Pat. Nos. 4,190,100 and 4,551,338 to Wallace; Borchet et al., “Prevention of Pale, Soft Exudative Porcine Muscle Through Partial Freezing with Liquid Nitrogen Post-Mortem”, J. Food Science 29 (2): 203–209 (1964); and E. J. Briskey, “Etiological Status and Associated Studies of Pale, Soft, Exudative Porcine Musculature”, Adv. Food Research, 13: 159–167 (1964). More recently, U.S. Pat. No. 5,085,615 to Gundlach et al. described the use of solid carbon dioxide to reduce the development of PSE characteristics in freshly killed meat. While the above cited-art describes various methods of preventing the development of PSE characteristics in meat, none of them describe a procedure for lessening, reversing or repairing the effects of PSE once it has occurred. That is, the art does not describe a process whereby meat cuts or chunks or grinds which have developed or begun to develop PSE characteristics may be treated to lessen, reverse or repair the PSE process or the effects of the PSE process such that the quality of pale, soft and exudative (PSE) meat improves and becomes more nearly like those of normal meat.
Japanese patent publications describing the use of TG are No. 06261692A (preparation of animal feeds by allowing TG to act upon the meat of animals, fish and/or their by-products which are used as such feeds); No. 6225729A (addition of TG to ground fish or cattle meat); No. 6197738A (addition of TG to ground meat for making hamburgers); No. 6113796A (addition of TG to paste food for making sausages or hamburgers of fish meats); No. 6090710A (using thrombin in combination with plasma protein, fibrinogen concentrate, fibrinogen or transglutaminase plasma); No. 5207864A (use of transglutaminase to improve meat color); No. 3210144A (use of transglutaminase with canned, or potted meat, fish, crab and scallop products); No. 2255060A (adding transglutaminase to minced meat or fish paste products); No. 2100655A (addition of transglutaminase to ground fish meat); and No. 2100654A (addition of transglutaminase to ground ‘okiama’ (Euphausia superba) fish to improve the water retention and smoothness of the finished ground product). Additional Japanese patent publications describing the use of transglutaminase are Nos. 2100653A, 2100651A, 2086748A and 2079956A, all of which describe the use of transglutaminase with ground fish or meat pastes.